title: Treatment with the immunomodulator FTY720 does not promote spontaneous bacterial infections after experimental stroke in mice.
abstract: BACKGROUND
  FTY720, an immunomodulator derived from a fungal metabolite which reduces circulating lymphocyte counts by increasing the homing of lymphocytes to the lymph nodes has recently gained interest in stroke research. The aim of this study was to evaluate the protective efficacy of FTY720 in cerebral ischemia in two different application paradigms and to gather first data on the effect of FTY720 on the rate of spontaneous bacterial infections in experimental stroke.
  
  
  METHODS
  Middle cerebral artery occlusion (MCAO) in C57BL/6 mice (strain J, groups of 10 animals) was performed with two different durations of ischemia (90 min and 3 h) and FTY720 was applied 2 h after vessel occlusion to study the impact of reperfusion on the protective potency of FTY720. Lesion size was determined by TTC staining. Mice treated with FTY720 or vehicle were sacrificed 48 h after 90 min MCAO to determine the bacterial burden in lung and blood.
  
  
  RESULTS
  FTY720 1 mg/kg significantly reduced ischemic lesion size when administered 2 h after the onset of MCAO for 3 h (45.4 ± 22.7 mm3 vs. 84.7 ± 23.6 mm3 in control mice, p = 0.001) and also when administered after reperfusion, 2 h after the onset of MCAO for 90 min (31.1 ± 28.49 mm3 vs. 69.6 ± 27.2 mm3 in control mice, p = 0.013). Bacterial burden of lung homogenates 48 h after stroke did not increase in the group treated with the immunomodulator FTY720 while there was no spontaneous bacteremia 48 h after MCAO in treated and untreated animals.
  
  
  CONCLUSIONS
  Our results corroborate the experimental evidence of the protective effect of FTY720 seen in different rodent stroke models. Interestingly, we found no increase in bacterial lung infections even though FTY720 strongly reduces the number of circulating leukocytes.
authors.affiliation: Department of Neurology, University Hospital, Goethe University Frankfurt am Main, Germany. w.pfeilschifter@med.uni-frankfurt.de.
authors.forename: Waltraud
authors.initials: W
authors.lastname: Pfeilschifter
authors.forename: Bożena
authors.initials: B
authors.lastname: Czech-Zechmeister
authors.forename: Marian
authors.initials: M
authors.lastname: Sujak
authors.forename: Christian
authors.initials: C
authors.lastname: Foerch
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Wichelhaus
authors.forename: Josef
authors.initials: J
authors.lastname: Pfeilschifter